TI Chronos watch monitor your sleeping infant

[Bill] wants a little piece of mind when his infant is sleeping in the other room. For him, the audio-only baby monitor could use some improvement. His proof-of-concept is that blue patch Velcroed on the swaddled infant. It monitors movement, orientation, and temperature and alerts you when something’s amiss.

Inside the pouch you’ll find a TI Chronos eZ430 wristwatch with the band removed. It’s a nice hardware choice because it includes an accelerometer, temperature sensor, and RF link to a USB dongle. [Bill’s] code sends a data packet to the PC about once a second. The PC watches to make sure there’s slight motion, indicating the baby is breathing. This part doesn’t work all that well as the accelerometer doesn’t pick up tiny movements all too well, but it does have potential. In the video after the break you can see the functions which make sure the baby doesn’t roll onto its belly, and that she’s not too cold do work extremely well.

We wonder if the accelerometer would pick up more motion if the watch was hung from a string inside of a small enclosure. This way it would swing back and forth with small movements. But perhaps that would make the whole thing too bulky?

The company Angelcare has a baby motion sensor which is rather low-tech; it uses a pad underneath the mattress/sheet to pick up motion. This information is then added to the audio data & temperature sent on their RF channel.

With the concerns about the possibl harmful effects of radio signals at close proximity, (read mobile phones), is it wise to attach such a device to so young a child?

Even if this does not concern you to greatly, why do you need to transmit data every second? Seems like incredible overkill, surely the build could be just as effective with telemetry delivered on the minute, or when there is significant change.

It measures: Movement, Orientation, Temperature. If death is the criteria, well then breathing is the crucial measurement, modern first aid states that if there is no breathing, there is no heartbeat. Because temperature won’t be helping you until it is too late, and orientation means stuff all. Nothing has to actually be transmitted unless the infant stops breathing, or the orientation changes indicating the child is on their stomach.

And if you had read my second paragraph, I was not proposing such a ridiculous interval as your hour.

What happens if the RF’s end up triggering cot death?
There are many listed risk factors, but no known causes for Sudden Infant Death Syndrome.
Anyway, my real concern is that having RF energy, at any strength, going off so constantly, and at such a close proximity, to an infant’s developing brain, may not be entirely wise.

Are you crazy? Even if the baby does not get RF directly from the baby, he will from the thousands of other sources of RF – like public radio emitters, satellites and a multitude of other consumer materials. Heck! Even power supply transformers produce a RF signal more powerful than the chronos!

The chronos is rated for RF communication of just a few meters, you cannot really compare one with a cellphone which communicates with cell towers kilometers away!

Next time before making stupid observations, think if a RF SoC that sources 3V from a single button cell (and lasts for months) can really output the >2W HF signal that cellphones do.

With baby monitoring, you want regular transmissions as a ‘ping’ to know that the transmitter is still working. It’s amazing how well your baby seems to sleep when you forgot to plug the transmitter into the charger… :P

I wouldn’t be overly concerned about sporadic use of the Chronos near the baby, but I wouldn’t characterize the question as ‘crazy’, either. For instance, ask TI if they recommend placing the Chronos near an infant for hours a day over months of time. They might use ‘crazy’ in their reply in the opposite sense of the previous reply.
Commercial products of this type appear to use a sensor under the baby connected to a device nearby that does RF linking.
The multiple types of sensors of the Chronos make it great for a proof-of-concept test, but if I wanted to use this every day, I’d separate the sensors and the RF portions of the circuit – even a foot or 18″ would make a big difference on RF dose to the baby.

The problem he’s having is actually the same problem with commercial devices; if you have a particularly still baby the device will constantly go off. These devices imply they are monitoring breathing, but in reality they only detect much larger movements which indicate the child is still breathing. With my own child on the way I have been thinking about this very same type of problem. A pulse oximeter might be a better way to monitor whats happening but that kind of defeats the point of the easy TI chronos baby monitor.

These issues pulled me into using microcontrollers, on inspiration from Dr.K, whom no one reading will remember.

However, the problem now is the same problem from 4 decades ago, which is that pad monitors don’t work. You can do it with an 8008, or you can do it with an arduino, but in the end, they’re almost useless.

Pad sensors don’t help with SIDS. Babies still die from various causes, and these devices are all but useless for anything other than demos.